PN> > That is, the studies which I have cited repeatedly disproves
PN> >the assumption that bipedalism is less efficient that quadrupedalism at
PN> >least when it comes to walking. The measurments were taken on
PN> chimpanzees
PN> >because they are living and it is somewhat difficult to take these
PN> >readings on fossils.

Pa> Energy efficient or survival efficient?

Pa> Is an ape going through the process
Pa> of radically altering its pelvic structure, the length of its legs, its
Pa> internal
Pa> anatomy, the shape of its spine, the position of its skull, and all the
Pa> other
Pa> structural changes associated with true bipedalism, going to be as
Pa> efficient at
Pa> bipedalism as quadrupedalism during that process?

Here you are making the entirely unwarranted assumption that the CA was
quadrupedal. But even so, it's a red herring, anyway, because it's
related to a topic you brought back from the past:

Pa> Evolution doesn't give you a sub-optimal holiday while you evolve an
Pa> optimal solution - the principle of non-disadvantageous intermediates.

There is no such "principle", as has been pointed out to you many many
many many times so far. The idea that evolution produces "optimal"
behaviors or morphology is a popular misconception, but that's all it
is. Evolution does not force "optimal" results, it selects against
ones that don't work "well enough". The sooner you divorce the words
"optimal" and "evolution" from each other, the closer you'll be to an
understanding of evolutionary principles.

PN> >My point is that the common ancestor was not a knuckle-walker as has
PN> >been fairly well demonstrated, that it was most likely an arboreal
PN> >ape (clearly indicated by Lucy's limb bone proportions and curved
PN> >toes) and very likely a suspensory feeder. The latter adapation
PN> >would predispose it to be a biped when it moved on the round, much
PN> >the same as gibbons and spider monkeys who are modern suspensory
PN> >feeders. This is not to imply that humans are descended from either
PN> >spider monkeys or gibbons.

This is really laughable; two people don't want to use data from spider
monkeys and gibbons because they're "too far removed" from us. Instead
they want to compare us with whales, dolphins, pigs, hippos (both
regular and pygmy), seals, and "any hairless aqautic mammal", not to
mention (at least somewhat closer to home) Japanese macaques and
proboscis monkeys.

Pa> I think you are putting yourself out on a limb by claiming Lucy was
Pa> a suspensory feeder. There is no earthly reason why such a
Pa> suspensory feeder should become bipedal in the human sense.

There is no earthly reason why anything *should* happen in any given
way, according to evolutionary theory. The path taken is only seen in
hindsight. You are showing another example of your misunderstanding of
evolutionary principles.

Pa> (Standing or walking on two legs for short periods does not
Pa> qualify as bipedalism, despite what some posters claim.)
Pa> Pat D

It isn't full-time bipedalism, but it is bipedalism. What would you
call it?